P2773

Code

Generic P — Powertrain

Four Wheel Drive (4WD) Low Switch Circuit Low

Brand: Generic

Type: P — Powertrain

Views: UK: 20 EN: 34 RU: 40

AI status

Completed

ready

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Page language: EN

Causes

Failed 4WD-low position switch
Short to ground in the 4WD-low switch signal wire
Open or high-resistance connection in the switch harness
Corroded or loose connector at the switch or control module
Poor ground for the transfer case/4WD control circuit
Faulty transfer case control module or PCM input

Symptoms

4WD-low indicator lamp may not illuminate or may be incorrect
Inability to engage 4WD low range or transfer case won’t shift into low
MIL/Check Engine Light set with P2773 stored
Intermittent loss of 4WD-low function or erratic 4WD behavior
Possible limp or reduced drivetrain function depending on vehicle

What to check

Scan for P2773 and any related transfer case or transmission codes; record freeze frame/conditions
Inspect the 4WD-low switch connector and wiring for corrosion, damage, or water intrusion
Visually inspect transfer case area and mounting grounds for loose or corroded connections
Check fuses and power supply to transfer case/4WD control circuits
Wiggle test wiring and connector while monitoring live data or EVT for changes
Check for related active tests in the scan tool to monitor switch status while commanding transfer case

Signal parameters

Nominal reference/supply voltage to switch: ~12V (key ON) or vehicle-specific reference (often 5V)
Expected switch output when not indicating low: open/high or supply-level (vehicle dependent)
Expected switch output when indicating low: near 0V (grounded) or low voltage state
Closed-switch continuity (when engaged) typically
Resistance between switch ground and chassis ground: close to 0 ohms

Diagnostic algorithm

Verify and record freeze-frame data and any additional codes. Confirm ignition state and vehicle conditions when code set.
Perform a visual inspection of the 4WD-low switch connector, wiring harness, and transfer case for corrosion, damage, or water entry. Repair obvious issues.
Check fuses and power feed circuits for the transfer case controller/switch. Replace any blown fuses and retest.
Backprobe the switch connector with ignition ON (or as specified) and observe the reference/supply and signal voltages. Compare to expected signal parameters.
Operate the 4WD selector (or command transfer case via scan tool) while monitoring the switch signal. Note whether the signal changes state correctly when attempting to engage 4WD-low.
Check continuity/resistance of the switch circuit to the control module and to chassis ground. Look for shorts to ground or opens in the harness.
If wiring and connector inspect/test good, bench-test or substitute a known-good 4WD-low switch (or transfer case sensor) and repeat tests.
If switch replacement does not correct the fault, test or substitute the transfer case control module/PCM input and associated grounds. Repair wiring as needed.
Clear codes, perform function test and a road or operational test to confirm repair; rescan to ensure code does not return.

Likely causes

Failed or sticking 4WD-low position switch
Corrosion or damage at the switch connector
Pinched or chafed wiring shorted to ground
Bad ground at transfer case or chassis ground bolt

Fault status

⚠️ Status

Four Wheel Drive (4WD) Low Switch Circuit Low — the control module is detecting a low (grounded) signal on the 4WD-low position switch circuit when an alternate state is expected. This indicates an electrical or switch fault requiring inspection of the switch, wiring, connectors, and module inputs.

🟡 Repair difficulty: Medium

⏱️ Diagnostic time: 0.5-2.0 hours